basically a term used to describe an individual who does not do his fair share of work (eg. walking around talking, smoking, whatever else, but avoiding doing any actual work)

a person who "fucks the dog" or is "dog fucking" is

Intelligence agency term for "psychological operation". A government or corporate-sponsored operation, usually taking the form of a "terrorist attack" or "crazed gunman on a spree", with the intent of panicking the public into demanding more police and laws inhibiting freedom. Psyops are usually carried out by drugging a civilian or group of civilians with aggression-promoting drugs, psyching them up, arming them, and sending them out to commit mayhem. Government-sponsored terrorism. See also blackshirts, conspiracy

Fucking of at work.
see Milking the clock.

A stupid lazy son-of-a-bitch who sits around doing jack-shit all day, and mooch's weed off you like a motherfucker.

someone who fucks dogs

aka whitney wisconsin

A lazy person. See Fucking the dog.

An aircraft electrician serving the Royal Air Force.
WHY?
Because they do, there is an urban myth in the RAF that recounts a tale of an aircraft electrician that was caught having sex with a dog.